More than 4 million people have now clicked on a YouTube video that captures a confrontation on the West Side between a Manhattan family and a horde of motorcyclists. It’s a reminder of the chaos New York once had and may return to if we are not careful.

In the video, a gang of bikers forces a Range Rover driven by Alexian Lien — heading home with his wife and baby — to come to a stop. When he does, bikers block his vehicle, break a mirror and slash his tires. Lien accelerates and hits a number of bikers as he tries to get away. Some of the bikers give chase, and when they catch up with him in Washington Heights, they pull him out of his SUV and beat him. Meanwhile, a biker Lien ran over as he tried to get away is in the hospital with a broken spine.

Right now the DA and the cops are squabbling over charges. However it works out, authorities need to recognize that their primary obligation is to the law-abiding citizens of New York. This isn’t the first time motorcyclists have caused trouble or flouted the law. Such a group is a menace and ought to be recognized as such.

That’s what makes reports that cops are told not to crack down on bikers so troubling. An innocent man, woman and child guilty of nothing more than a Sunday drive found themselves stopped and terrorized by dozens of men on motorcyles trying to take over a public highway. The one who suffered terrible injuries in the process can thank his fellow bikers for that.

In sum, the bikers brought this on, and authorities need to bring them down.